High-Dimensional Manganese(II) Compounds with Noncovalent and/or Covalent Bonds Derived from Flexible Ligands:  Self-Assembly and Structural Transformation

1999 ◽  
Vol 38 (24) ◽  
pp. 5602-5610 ◽  
Author(s):  
Chang Seop Hong ◽  
Sang-Kil Son ◽  
Yoon Sup Lee ◽  
Moo-Jin Jun ◽  
Youngkyu Do
Keyword(s):  
Structural Transformation ◽  
Self Assembly ◽  
High Dimensional ◽  
Covalent Bonds ◽  
Flexible Ligands

Structural Transformation of a Germanium Σ=13 (510) [001] Tilt Grain Boundary under the Electron Beam

1990 ◽  
Vol 48 (1) ◽  
pp. 52-53 ◽  
Author(s):  
Jean-Luc Rouvière ◽  
Alain Bourret
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Structural Transformation ◽  
Mirror Symmetry ◽  
High Resolution Electron Microscopy ◽  
Structural Transformations ◽  
Covalent Bonds ◽  
Resolution Electron ◽  
Tilt Grain Boundary

The possible structural transformations during the sample preparations and the sample observations are important issues in electron microscopy. Several publications of High Resolution Electron Microscopy (HREM) have reported that structural transformations and evaporation of the thin parts of a specimen could happen in the microscope. Diffusion and preferential etchings could also occur during the sample preparation.Here we report a structural transformation of a germanium Σ=13 (510) [001] tilt grain boundary that occurred in a medium-voltage electron microscopy (JEOL 400KV).Among the different (001) tilt grain boundaries whose atomic structures were entirely determined by High Resolution Electron Microscopy (Σ = 5(310), Σ = 13 (320), Σ = 13 (510), Σ = 65 (1130), Σ = 25 (710) and Σ = 41 (910), the Σ = 13 (510) interface is the most interesting. It exhibits two kinds of structures. One of them, the M-structure, has tetracoordinated covalent bonds and is periodic (fig. 1). The other, the U-structure, is also tetracoordinated but is not strictly periodic (fig. 2). It is composed of a periodically repeated constant part that separates variable cores where some atoms can have several stable positions. The M-structure has a mirror glide symmetry. At Scherzer defocus, its HREM images have characteristic groups of three big white dots that are distributed on alternatively facing right and left arcs (fig. 1). The (001) projection of the U-structure has an apparent mirror symmetry, the portions of good coincidence zones (“perfect crystal structure”) regularly separate the variable cores regions (fig. 2).

scholarly journals Formation of Au-Silane Bonds

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Shira Yochelis ◽  
Eran Katzir ◽  
Yoav Kalcheim ◽  
Vitaly Gutkin ◽  
Oded Millo ◽  
...  
Keyword(s):  
Molecular Electronics ◽  
Self Assembly ◽  
Au Nanoparticles ◽  
Electrical Coupling ◽  
Gold Surface ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Fundamental Study ◽  
Covalent Bonds ◽  
Anchoring Groups

Many intriguing aspects of molecular electronics are attributed to organic-inorganic interactions, yet charge transfer through such junctions still requires fundamental study. Recently, there is a growing interest in anchoring groups, which considered dominating the charge transport. With this respect, we choose to investigate self-assembly of disilane molecules sandwiched between gold surface and gold nanoparticles. These assemblies are found to exhibit covalent bonds not only between the anchoring Si groups and the gold surfaces but also in plane crosslinks that increase the monolayer stability. Finally, using scanning tunneling spectroscopy we demonstrate that the disilane molecules provide strong electrical coupling between the Au nanoparticles and a superconductor substrate.

Self-assembly of high-dimensional architecture from Strandberg-type polyoxometalate clusters and silver ions

2012 ◽  
Vol 17 ◽  
pp. 155-158 ◽  
Author(s):  
Chun-Xia Zhang ◽  
Ya-Guang Chen ◽  
Qun Tang ◽  
Zhi-Chao Zhang ◽  
Dan-Dan Liu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Silver Ions ◽  
High Dimensional

scholarly journals Pillararenes Trimer for Self-Assembly

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 651 ◽  
Author(s):  
Huacheng Zhang ◽  
Zhaona Liu ◽  
Hui Fu
Keyword(s):  
Self Assembly ◽  
Driving Forces ◽  
Click Reaction ◽  
Noncovalent Interactions ◽  
Coupling Reaction ◽  
Covalent Bonds ◽  
Guest Molecules ◽  
Palladium Catalyzed ◽  
Noncovalent Bonds ◽  
External Stimuli

Pillararenes trimer with particularly designed structural geometry and excellent capacity of recognizing guest molecules is a very efficient and attractive building block for the fabrication of advanced self-assembled materials. Pillararenes trimers could be prepared via both covalent and noncovalent bonds. The classic organic synthesis reactions such as click reaction, palladium-catalyzed coupling reaction, amidation, esterification, and aminolysis are employed to build covalent bonds and integrate three pieces of pillararenes subunits together into the “star-shaped” trimers and linear foldamers. Alternatively, pillararenes trimers could also be assembled in the form of host-guest inclusions and mechanically interlocked molecules via noncovalent interactions, and during those procedures, pillararenes units contribute the cavity for recognizing guest molecules and act as a “wheel” subunit, respectively. By fully utilizing the driving forces such as host-guest interactions, charge transfer, hydrophobic, hydrogen bonding, and C–H…π and π–π stacking interactions, pillararenes trimers-based supramolecular self-assemblies provide a possibility in the construction of multi-dimensional materials such as vesicular and tubular aggregates, layered networks, as well as frameworks. Interestingly, those assembled materials exhibit interesting external stimuli responsiveness to e.g., variable concentrations, changed pH values, different temperature, as well as the addition/removal of competition guests and ions. Thus, they could further be used for diverse applications such as detection, sorption, and separation of significant multi-analytes including metal cations, anions, and amino acids.

Self-assembly of a Si-based cage by the formation of 24 equivalent covalent bonds

2018 ◽  
Vol 54 (84) ◽  
pp. 11877-11880 ◽  
Author(s):  
Jessica L. Holmes ◽  
Brendan F. Abrahams ◽  
Anna Ahveninen ◽  
Berin A. Boughton ◽  
Timothy A. Hudson ◽  
...  
Keyword(s):  
Self Assembly ◽  
Covalent Bonds

A covalent, robust, nano-sized tetrahedral cage containing six silicon centres has been synthesised and structurally characterised.

Template-Directed Syntheses of Catenanes

1997 ◽  
Vol 62 (4) ◽  
pp. 527-557 ◽  
Author(s):  
Martin Bělohradský ◽  
Françisco M. Raymo ◽  
J. Fraser Stoddart
Keyword(s):  
Self Assembly ◽  
Molecular Level ◽  
Covalent Bonds ◽  
Topological Features ◽  
Multistep Synthesis ◽  
Chance Event ◽  
Degree Of Control ◽  
High Degree ◽  
Acyclic Precursor ◽  
Molecular Compounds

The art and science of introducing mechanical-interlocking at the molecular level in order to generate catenanes - molecules composed of two or more macrocyclic components - offers the opportunity of constructing a new range of molecular compounds possessing intriguing properties. However, the topological features displayed by catenanes has rendered the syntheses of such molecular compounds an extremely challenging task for synthetic chemists to address. Their early syntheses were based upon either statistical approaches - the threading of a small amount of a macrocycle on to an acyclic precursor as a chance event - or directed approaches, relying upon the temporary introduction of covalent bonds in the multistep synthesis of a so-called precatenane, followed by its conversion ultimately into a catenane. These approaches afforded catenanes in very low yields overall and only after following tedious and laborious synthetic procedures. Fortunately, however, with the advent of supramolecular chemistry, template-directed methods that allow us to self-assemble [n]catenanes much more efficiently have become available. Numerous successful template-directed syntheses have now emerged - some by chance and others by design. These methods have been based upon (i) metal coordinating, (ii) hydrogen bonding, (iii) solvophobic, and/or (iv) π-π stacking interactions which have been found to govern self-assembly processes to catenated compounds from appropriate precursors. Their relative simplicity, the high degree of control with which they can be employed, and the remarkable efficiency with which they proceed has already provided the opportunity to synthetic chemists to self-assemble a series of [n]catenanes, incorporating from two up to five mechanically-interlocked macrocyclic components.

scholarly journals Self-assembly of a “double dynamic covalent” amphiphile featuring a glucose-responsive imine bond

2016 ◽  
Vol 52 (43) ◽  
pp. 6981-6984 ◽  
Author(s):  
Xin Wu ◽  
Xuan-Xuan Chen ◽  
Miao Zhang ◽  
Zhao Li ◽  
Philip A. Gale ◽  
...  
Keyword(s):  
Self Assembly ◽  
Covalent Bonds ◽  
Imine Bond

Glucose recognition via in situ formation of supramolecular vesicular aggregates that involve two dynamic covalent bonds.

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